Within the zone surrounding a plant's roots is a region called the rhizosphere. In the rhizosphere, bacteria, fungi, and other organisms compete for nutrients and for binding to the root structures of the plant. Both detrimental and beneficial bacteria and fungi can occupy the rhizosphere. The bacteria, fungi, and the root system of the plant can all be influenced by the actions of peptides, enzymes, and other proteins in the rhizosphere. Augmentation of soil or treatment of plants with certain of these peptides, enzymes, or other proteins would have beneficial effects on the overall populations of beneficial soil bacteria and fungi, create a healthier overall soil environment for plant growth, improve plant growth, and provide for the protection of plants against certain bacterial and fungal pathogens. However, previous attempts to introduce peptides, enzymes, and other proteins into soil to induce such beneficial effects on plants have been hampered by the low survival of enzymes, proteins, and peptides in soil. Additionally, the prevalence of proteases naturally present in the soil leads to degradation of the proteins in the soil. The environment around the roots of a plant (the rhizosphere) is a unique mixture of bacteria, fungi, nutrients, and roots that has different qualities than that of native soil. The symbiotic relationship between these organisms is unique, and could be altered for the better with inclusion of exogenous proteins. The high concentration of fungi and bacteria in the rhizosphere causes even greater degradation of proteins due to abnormally high levels of proteases and other elements detrimental to proteins in the soil. In addition, enzymes and other proteins introduced into soil can dissipate away from plant roots quickly.
Thus, there exists a need in the art for a method for effectively delivering peptides, enzymes, and other proteins to plants (e.g., to plant root systems) and for extending the period of time during which such molecules remain active. Furthermore, there exists a need in the art for a method of selectively targeting such peptides, enzymes, and proteins to the rhizosphere and to plant leaves and plant roots in particular.